1. Field of the Invention
This invention pertains broadly to the field of magnetic detection devices. More particularly, the invention pertains to a device for locating energized antenna ground-wires in the presence of a transmitting antenna.
2. Description of the Related Art
The U.S. Navy is interested in identifying causes of efficiency loss in its low frequency and very low frequency shore transmitters. It is known that some of these losses occur in a transmitter's antenna and, specifically, are due to breakage in conductors that compose a radially spreading ground-wire system for the antenna. As the number of ground-wire breaks increase, the radiation efficiency of a transmitter drops, adversely affecting the antenna's communication range.
The radiation efficiency of an antenna, and therefore of the entire transmitter, is dependent upon the electrical contact between the plane of buried antenna ground-wires and the earth. These ground planes are composed of hundreds of bare copper wires placed in the area around the antenna. The wires are often broken by subsequent earth work such as farming, utility connections, and landscaping.
A ground-wire detector can be used to locate the subterranean ground-wires before excavation work in the area is underway. In addition, a ground-wire detector can serve to identify where breaks in the buried ground-wires are located.
In the past, a portable instrument for detecting and locating ground-wires and their breaks was developed by the Navy. This unit worked on an autodyne principle and contained an oscillator section whose frequency was dependent in part upon two capacitors that had to be interchanged according to the frequency of the antenna system being studied. The need to alter this oscillator by way of component replacement posed field logistics problems that were considered undesirable.